Alfalfa is a perennial legume forage crop highly valued for its exceptional nutritional content, providing a rich source of protein for livestock. It is a significant component of Missouri’s agricultural economy, with hundreds of thousands of acres harvested annually for hay and feed. Successful establishment of an alfalfa stand is a multi-year investment that depends heavily on proper preparation and precise planting timing relative to the state’s distinct climate challenges. Achieving a vigorous, long-lasting stand requires attention to soil conditions, the correct season selection, and careful seeding techniques.
Preparing the Field for Alfalfa
A successful alfalfa stand requires specific attention to soil conditions, beginning long before the seed is sown. Alfalfa thrives in deep, fertile, and well-drained soils; fields with poor drainage or a history of standing water should be avoided. The most important initial step is a comprehensive soil test, conducted six to twelve months prior to the planned planting date.
Alfalfa is particularly sensitive to soil acidity, requiring a target pH between 6.5 and 7.0 for optimal growth and nutrient uptake. If the soil test reveals a need for lime, it must be applied well in advance, as lime reacts slowly and may take up to a year to fully adjust the pH level. The crop also has a high demand for phosphorus and potassium; required fertilizers should be incorporated based on test recommendations to support developing seedlings.
Weed management is equally important, particularly controlling perennial weeds, which should ideally be addressed the year before planting. The seedbed requires a firm, fine, and level surface to ensure good seed-to-soil contact and consistent planting depth. Final preparation should leave the soil firm enough that a footprint sinks no deeper than about a half-inch, preventing the seedbed from drying out quickly and hindering germination.
Optimal Planting Seasons in Missouri
The choice of planting season is the single largest factor determining stand success in Missouri, with two primary windows available to growers. The preferred period is fall planting, generally spanning from mid-August through mid-September. This timing is favored because emerging seedlings face less competition from annual weeds, which slow their growth as the season cools.
Late-summer planting allows the alfalfa to establish a deep, robust taproot system and a well-developed crown before the first hard frost. This root development is crucial for winter survival, as seedlings need six to eight weeks of growth to build up carbohydrate reserves. Planting after mid-September significantly increases the risk of winterkill because the plants will not have sufficient time to harden off.
Spring planting is the alternative, with the window opening from late March to mid-April, and earlier dates preferred in southern Missouri. While this option allows seedlings to establish during reliable moisture, it presents a higher risk due to increased weed pressure. Spring-planted alfalfa must compete directly with vigorously growing summer annual weeds, which can quickly smother the young legumes. Another drawback is the potential for hot, dry summer conditions to stress young plants before their taproots are fully developed. Fall planting is generally the most reliable strategy for maximizing stand life and first-year yield potential.
Establishing the Stand Successfully
Once the field is prepared and the optimal planting window arrives, specific seeding techniques must be employed for successful stand establishment. The recommended seeding rate for a pure alfalfa stand is between 12 and 18 pounds of pure live seed per acre. Using a slightly higher rate, such as 15 to 18 pounds, can help compensate for less-than-perfect soil conditions and improve competition against weeds.
Seed inoculation is a non-negotiable step for all new alfalfa plantings, especially if the field has not recently grown alfalfa. Seeds must be treated with the correct strain of Rhizobium bacteria, which form nodules on the roots for symbiotic nitrogen fixation. This process allows the alfalfa to utilize atmospheric nitrogen, eliminating the need for applied nitrogen fertilizer.
The depth of planting is extremely important, as alfalfa seeds are small and have limited energy reserves for emergence. The seed should be placed no deeper than one-quarter to one-half inch in fine-textured or loam soils. Planting deeper than one-half inch can prevent the seedling from reaching the soil surface, while planting too shallow risks the seed drying out. After seeding, the field should be rolled or cultipacked to firm the soil around the seed, promoting necessary seed-to-soil contact for rapid germination.
Initial management must focus on controlling weeds, which are the biggest threat to newly established stands, especially those planted in the spring. Post-emergence herbicides can be applied once the alfalfa seedlings reach the first or second trifoliate leaf stage, depending on the product label. Protecting the young stand from weed competition during this early stage ensures the stand remains dense and productive for its full lifespan.